This invention relates in general to vehicular drive train systems including a driveshaft assembly for transferring rotational power from an engine/transmission assembly to an axle assembly. In particular, this invention relates to an improved structure for such a vehicular driveshaft assembly.
In most land vehicles in use today, a drive train system is provided for transmitting rotational power from an output shaft of an engine/transmission assembly to an input shaft of an axle assembly so as to rotatably drive one or more wheels of the vehicle. To accomplish this, a driveshaft assembly is connected between the output shaft of the engine/transmission assembly and the input shaft of the axle assembly. The driveshaft assembly can include a driveshaft tube, the ends of which can be connected to the output shaft of the engine/transmission assembly and the input shaft of the axle assembly by respective universal joints. Such universal joints are well known in the art and provide a rotational driving connection therebetween, while accommodating a limited amount of angular misalignment between the rotational axes of the various shafts. The connection between the ends of the driveshaft tube and the universal joints is usually accomplished by tube yokes disposed within the ends of the driveshaft tube. Each tube yoke typically includes a tube seat at one end and a lug structure at the other end. The tube seat is a generally cylindrical-shaped member that is adapted to be inserted into an open end of the driveshaft tube. Accordingly, the tube seat enables torque to be transmitted between the driveshaft tube and the tube yoke.
In known driveshaft assemblies, the tube yoke is secured to the driveshaft tube by a ring weld. The ring weld is a circular weld that extends about the entire circumference of the joint between the tube yoke and the driveshaft tube. The ring weld extends throughout a single plane that is perpendicular to the central axis of the driveshaft tube. As a result, all of the torsional shear stresses that are encountered during operation of the driveshaft assembly are applied in that circumferential plane. Thus, the ring weld must be sufficiently strong as to be capable of accommodating all of such torsional shear stresses that are generated in that single perpendicular plane during operation. Although this type of weld has been effective, it would be desirable to provide an improved structure for such a weld between a tube yoke and a driveshaft tube that is capable of accommodating a greater amount of such torsional shear stresses and, therefore, increases the load carrying capacity of the driveshaft assembly.